This invention relates in general to battery chargers, and more specifically to a battery charger for charging a plurality of cells connected in series with one another.
Batteries often are made up of a plurality of individual cells, or portions, connected in series to achieve a desired overall battery voltage. In some kinds of batteries, e.g., lithium ion batteries, when bulk charging the overall battery, the individual cells can charge at different rates. Once a first individual cell reaches full charge, the bulk charging process must stop to avoid overcharging. This can leave other individual cells at less than full capacity.
In addition, some applications can have circuitry that requires more than one supply voltage for its operation. In such applications, the overall battery voltage supplied from all battery portions in series can be utilized for some of the circuitry, while a fraction of the battery portions can be utilized to power other parts of the circuitry at a lower voltage. Such applications can produce an asymmetrical loading on the battery portions, leaving some battery portions more depleted than others.
Thus, what is needed is a battery charger that can bring all the individual cells, or battery portions, up to full capacity without overcharging the battery.
An aspect of the present invention is a battery charger for charging a plurality of cells connected in series with one another. The battery charger comprises a plurality of cell chargers, each cell charger having an output that is electrically floating with respect to a direct current (DC) power source utilized to power the cell charger. The cell charger is arranged to be coupled in parallel with a corresponding one of the plurality of cells. The battery further comprises a controller coupled to the plurality of cell chargers for controlling the plurality of cell chargers.
Another aspect of the present invention is a battery charger for charging a plurality of battery portions connected in series with one another, with a battery portion comprising at least one cell. The battery charger comprises a plurality of battery portion chargers, each battery portion charger having an output that is electrically floating with respect to a direct current (DC) power source utilized to power the battery portion charger. The battery portion charger is arranged to be coupled in parallel with a corresponding one of the plurality of battery portions. The battery charger further comprises a controller coupled to the plurality of battery portion chargers for controlling the plurality of battery portion chargers.
A third aspect of the present invention is a cell charger for a battery charger for charging a plurality of cells connected in series with one another. The cell charger comprises an output that is electrically floating with respect to a direct current (DC) power source utilized to power the cell charger. The cell charger is arranged to be coupled in parallel with a corresponding one of the plurality of cells. The cell charger further comprises a controller interface for interfacing with a controller for controlling the cell charger.
A fourth aspect of the present invention is a battery portion charger for a battery charger for charging a plurality of battery portions connected in series with one another, with a battery portion comprising at least one cell. The battery portion charger comprises an output that is electrically floating with respect to a direct current (DC) power source utilized to power the battery portion charger. The battery portion charger is arranged to be coupled in parallel with a corresponding one of the plurality of battery portions. The battery portion charger further comprises a controller interface for interfacing with a controller for controlling the battery portion charger.